feat(saas): Phase 2 Admin Web 管理后台 — 完整 CRUD + Dashboard 统计

后端:
- 添加 GET /api/v1/stats/dashboard 聚合统计端点
  (账号数/活跃服务商/今日请求/今日Token用量等7项指标)
- 需要 account:admin 权限

Admin 前端 (Next.js 14 + shadcn/ui + Tailwind + Recharts):
- 设计系统: Dark Mode OLED (#020617 背景, #22C55E CTA)
- 登录页: 双栏布局, 品牌区 + 表单
- Dashboard 布局: Sidebar 导航 + Header + 主内容区
- 仪表盘: 4 统计卡片 + AreaChart 请求趋势 + BarChart Token用量
- 8 个 CRUD 页面:
  - 账号管理 (搜索/角色/状态筛选, 编辑/启用禁用)
  - 服务商 (CRUD + API Key masked)
  - 模型管理 (Provider筛选, CRUD)
  - API 密钥 (创建/撤销, 一次性显示token)
  - 用量统计 (LineChart + BarChart)
  - 中转任务 (状态筛选, 展开详情)
  - 系统配置 (分类Tab, 编辑)
  - 操作日志 (Action筛选, 展开详情)
- 14 个 shadcn 风格 UI 组件 (手写实现)
- 类型化 API 客户端 (SaaSClient, 20+ 方法, 401 自动跳转)
- AuthGuard 路由保护 + useAuth() hook

验证: tsc --noEmit 零 error, pnpm build 13 页面成功, cargo test 21 通过

admin/src/components/ui/dialog.tsx

@@ -0,0 +1,118 @@
+'use client'
+
+import * as React from 'react'
+import * as DialogPrimitive from '@radix-ui/react-dialog'
+import { X } from 'lucide-react'
+import { cn } from '@/lib/utils'
+
+const Dialog = DialogPrimitive.Root
+const DialogTrigger = DialogPrimitive.Trigger
+const DialogPortal = DialogPrimitive.Portal
+const DialogClose = DialogPrimitive.Close
+
+const DialogOverlay = React.forwardRef<
+  React.ElementRef<typeof DialogPrimitive.Overlay>,
+  React.ComponentPropsWithoutRef<typeof DialogPrimitive.Overlay>
+>(({ className, ...props }, ref) => (
+  <DialogPrimitive.Overlay
+    ref={ref}
+    className={cn(
+      'fixed inset-0 z-50 bg-black/60 backdrop-blur-sm',
+      'data-[state=open]:animate-in data-[state=closed]:animate-out',
+      'data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0',
+      className,
+    )}
+    {...props}
+  />
+))
+DialogOverlay.displayName = DialogPrimitive.Overlay.displayName
+
+const DialogContent = React.forwardRef<
+  React.ElementRef<typeof DialogPrimitive.Content>,
+  React.ComponentPropsWithoutRef<typeof DialogPrimitive.Content>
+>(({ className, children, ...props }, ref) => (
+  <DialogPortal>
+    <DialogOverlay />
+    <DialogPrimitive.Content
+      ref={ref}
+      className={cn(
+        'fixed left-[50%] top-[50%] z-50 grid w-full max-w-lg translate-x-[-50%] translate-y-[-50%]',
+        'gap-4 border border-border bg-card p-6 shadow-lg duration-200',
+        'data-[state=open]:animate-in data-[state=closed]:animate-out',
+        'data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0',
+        'data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95',
+        'data-[state=closed]:slide-out-to-left-1/2 data-[state=closed]:slide-out-to-top-[48%]',
+        'data-[state=open]:slide-in-from-left-1/2 data-[state=open]:slide-in-from-top-[48%]',
+        'rounded-lg',
+        className,
+      )}
+      {...props}
+    >
+      {children}
+      <DialogPrimitive.Close className="absolute right-4 top-4 rounded-sm opacity-70 ring-offset-background transition-opacity hover:opacity-100 focus:outline-none focus:ring-2 focus:ring-ring focus:ring-offset-2 disabled:pointer-events-none data-[state=open]:bg-accent data-[state=open]:text-muted-foreground">
+        <X className="h-4 w-4" />
+        <span className="sr-only">Close</span>
+      </DialogPrimitive.Close>
+    </DialogPrimitive.Content>
+  </DialogPortal>
+))
+DialogContent.displayName = DialogPrimitive.Content.displayName
+
+const DialogHeader = ({
+  className,
+  ...props
+}: React.HTMLAttributes<HTMLDivElement>) => (
+  <div
+    className={cn('flex flex-col space-y-1.5 text-center sm:text-left', className)}
+    {...props}
+  />
+)
+DialogHeader.displayName = 'DialogHeader'
+
+const DialogFooter = ({
+  className,
+  ...props
+}: React.HTMLAttributes<HTMLDivElement>) => (
+  <div
+    className={cn('flex flex-col-reverse sm:flex-row sm:justify-end sm:space-x-2', className)}
+    {...props}
+  />
+)
+DialogFooter.displayName = 'DialogFooter'
+
+const DialogTitle = React.forwardRef<
+  React.ElementRef<typeof DialogPrimitive.Title>,
+  React.ComponentPropsWithoutRef<typeof DialogPrimitive.Title>
+>(({ className, ...props }, ref) => (
+  <DialogPrimitive.Title
+    ref={ref}
+    className={cn('text-lg font-semibold leading-none tracking-tight', className)}
+    {...props}
+  />
+))
+DialogTitle.displayName = DialogPrimitive.Title.displayName
+
+const DialogDescription = React.forwardRef<
+  React.ElementRef<typeof DialogPrimitive.Description>,
+  React.ComponentPropsWithoutRef<typeof DialogPrimitive.Description>
+>(({ className, ...props }, ref) => (
+  <DialogPrimitive.Description
+    ref={ref}
+    className={cn('text-sm text-muted-foreground', className)}
+    {...props}
+  />
+))
+DialogDescription.displayName = DialogPrimitive.Description.displayName
+
+export {
+  Dialog,
+  DialogPortal,
+  DialogOverlay,
+  DialogClose,
+  DialogTrigger,
+  DialogContent,
+  DialogHeader,
+  DialogFooter,
+  DialogTitle,
+  DialogDescription,
+}